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E55L

Sensibly equivalent to:
8233 CV5808
    
Extras ▼

 

The E55L all glass special quality pentode from Mullard was designed as a high gain low impedance video/wide-band output valve. Our specimen was found in a Tektronix oscilloscope vertical amplifier. Its function was as the Y amplifier's final stage. One of these valves was used per channel to drive the CRT plates.
The Mullard description of this valve is 'Special quality high slope output pentode intended for general industrial applications where stability of characteristics and long life are required.
The data sheets give absolute maximum ratings and these appear in the second table. Additionally for operation with a shorter life the maximum cathode current can be extended to 100 mA. The bulb maximum temperature can also be increased from 180 C to 220 C under reduced life conditions.
The gm has a very high value, which both makes the wide-band capabilities possible and makes testing of used valves difficult.
Visual inspection shows that within the anode cavity are beam plates even though the device is quoted as a pentode. The screen grid is formed from a parallel series of very fine wires. The control grid is too close to the cathode to be seen. As is typical of special quality valves the base pins are gold plated to give low contact resistance and resist corrosion.
Outside the central core of cathode and inner two grids are the bright beam forming plates and finally the blackened anode.
The anode is shaped such that a small flat section is close to the electron stream passing through the beam plates but the rest of the anode is further away.
The wide glass tube envelope is 26 mm in diameter and, excluding the B9D base pins, is 57 mm tall.
Reference: Datasheet & 3002. Type E55L was first introduced in 1960.

 

Pin Connections
B9D
1
2
3
4
5
6
7
8
9
a
g3
g2
h
h
g3
k
g1
k

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.6
200
175
-55
50
5.5
20k
45

 

Absolute Maximum Operating Conditions
Pentode
Va
Vs
Vg
mAa
mAs
ra
gm
Pdiss
400
175
-55
70
5.5
20k
45
10W
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated April 20, 2015.
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